// Program to desmonstrate simple decision tree

import java.awt.*;
import java.awt.event.*;

public class CarD extends java.applet.Applet implements ActionListener
{
    TextField mQuery, mAnswer;
    Button bYes, bNo;
    int location;

    public void init()
    {
	mQuery = new TextField(70);
  	mQuery.setText("Was your car just now running before it quit?");
  	bYes = new Button("Yes");
  	bNo = new Button("No");
        location = 0;
  	mAnswer = new TextField(70);
        bYes.addActionListener(this);
        bNo.addActionListener(this);
  	add(mQuery) ;
  	add(bYes) ;
  	add(bNo) ;
  	add(mAnswer) ;
    }

    public void actionPerformed(ActionEvent event)
    {
        Object cause = event.getSource();
        if (cause == bYes)
        {
            if (location == 0)
            {
                 location = 1;
  	         mQuery.setText("Is the gas gauge on empty?");
            }
            else if (location == 1)
            {
                 location = 3;
  	         mAnswer.setText("Better find some gas.");
            }
            else if (location == 2)
            {
                 location = 5;
  	         mAnswer.setText("Maybe you should check the gas.");
            }
        }
        if (cause == bNo)
        {
            if (location == 0)
            {
                 location = 2;
  	         mQuery.setText("Does the engine crank?");
            }
            else if (location == 1)
            {
                 location = 4;
  	         mAnswer.setText("Messy. Call a tow truck.");
            }
            else if (location == 2)
            {
                 location = 6;
  	         mAnswer.setText("Looks like a dead battery.");
            }
        }
    }	
}